Small 11Kv cable fire London...

[Knobhead]

I was referring to the transformers I’ve worked on.

They still use 6.6 in London and parts of the NW. That wasn’t what I was reading about last night.

It was system reliability I was interested in. I set off looking for E/F passage indicators. That led on to automatic switching for RMU’s.

 

[UKMeterman]

To increase "reliablity of supply" in the "City" the LV supplies are fed from two MV transformers and have a reverse power relays and ACB at each sub station. This means that the LV fault level is very high, I wonder if this has added to the intenensity of the pavement explosions and so on.

 

[Engineer54]

To increase "reliablity of supply" in the "City" the LV supplies are fed from two MV transformers and have a reverse power relays and ACB at each sub station. This means that the LV fault level is very high, I wonder if this has added to the intenensity of the pavement explosions and so on.

From my understanding, the fault levels are very high throughout Central London and the City of London.
The fire as far as i can see is located in the West End (Central London) not in the City...

 

[UKMeterman]

Have a google for
[h=2]Search Results[/h][h=3][PDF]Long Term Development Statement - UK Power Networks[/h]

 

[Engineer54]

Have a google for
Search Results

[PDF]Long Term Development Statement - UK Power Networks

An interesting read, though quite a bit of waffle is going on in that report. I wonder what they actually mean by ''Long Term Development'' because the areas i've already pointed out have been in dire need of development since i was a lad. As i said the costs involved, especially in Central London are going to be astronomical and must be scaring the crap out of these private companies, that will probably move on before any real work is undertaken....

 

[Knobhead]

To increase "reliablity of supply" in the "City" the LV supplies are fed from two MV transformers and have a reverse power relays and ACB at each sub station. This means that the LV fault level is very high, I wonder if this has added to the intenensity of the pavement explosions and so on.

I was reading about it last night after I found the fault passage indicator info I needed. I got reading about the MV protection and automatic switching.

It’s highly unlikely they’ll run transformers in parallel, purely down to the fault currents local to the substation. You have to take in to account the low system impedance on the MV side feeding in to the transformer.

There was another well publicised incident recently where a LV UG link box failed. It could have been O/L or water ingress which some are prone to. I know one thing, I don’t like them.

From my understanding, the fault levels are very high throughout Central London and the City of London.
The fire as far as i can see is located in the West End (Central London) not in the City...

The line to line fault currents will be high, at least using NER’s the line to earth current can be limited.

 

[Engineer54]

I was reading about it last night after I found the fault passage indicator info I needed. I got reading about the MV protection and automatic switching.

It’s highly unlikely they’ll run transformers in parallel, purely down to the fault currents local to the substation. You have to take in to account the low system impedance on the MV side feeding in to the transformer.

There was another well publicised incident recently where a LV UG link box failed. It could have been O/L or water ingress which some are prone to. I know one thing, I don’t like them.




The line to line fault currents will be high, at least using NER’s the line to earth current can be limited.

As i say, i think the patch and fix thats been going on for years will continue, with no real effort in sorting out the distribution system as a whole. In Central London the main problem is space and being able to maintain supplies while they are installing the new upgraded system. ...And of course the costs involved, that will just keep getting bigger the longer they leave it and keep installing patching work...

 

[UKMeterman]

Hi,
I have seen some new 132KV subs being installed on the outskirts of the city (Finsbury) and there have been other changes.
As to Tony's point please read the document I linked to, the two transformers in parrell is exactly what they are doing...!

 

[Engineer54]

Hi,
I have seen some new 132KV subs being installed on the outskirts of the city (Finsbury) and there have been other changes.
As to Tony's point please read the document I linked to, the two transformers in parrell is exactly what they are doing...!

Not exactly a good practice though is it? Looking at those single line drawings in the link, isn't instilling any confidence on my part in the security of network systems they are currently supplying...

It's the Central London distribution networks that need a total overhaul, where there is just no space to accommodate upgrading. Finsbury, or other outskirt areas is another world compared to congested areas of London...

 

[Knobhead]

Hi,
I have seen some new 132KV subs being installed on the outskirts of the city (Finsbury) and there have been other changes.
As to Tony's point please read the document I linked to, the two transformers in parrell is exactly what they are doing...!

Learn to read drawings.
The transformers that look like they are in parallel are feeding the 11KV network. They are dual star secondary. They aren’t separate units in parallel.

I was referring to LV being in parallel. The MaxPFC would exceed the LV pillars rating.
Some LV pillars incorporate automatic change over of transformers, the MG SAIF springs to mind.

 

[Knobhead]

UKMeterman,

Try reading UKPN’s network design manual.

 

[jay sean]

I worked at Hyde substation (NG) and they give the electricity out at 66KV how does that work, knowing NG feed into DNO at 132Kv

Once a SAP at NG said they need to install more substations in the outskirts of London to keep up with demand

 

[Knobhead]

Step up autotransformers 1/2 ratio

 

[UKMeterman]

Tony, have a look at https://www.google.co.uk/url?sa=t&r...86DjYs7Yqydhin49qdiO0NA&bvm=bv.89947451,d.bGg

UK PN EDS 08-0119

section 7.3, not sure what to make of it and also section 7.2 of https://www.google.co.uk/url?sa=t&r...syQJzWWKtQKE43A&bvm=bv.89947451,d.d2s&cad=rja

UK PN EDS 08-0119

Thanks

 

[Knobhead]

What is your job with UKPN?

 

[UKMeterman]

Hi,
I don't work for UKPN.

 

[SPARTYKUS]

At last! An interesting thread....

 

[Knobhead]

Hi,
I don't work for UKPN.

OK, so what do you do?

The links you posted I already have on file so no need for me to look on Google.